X chromosome may control male fertility

In the past, researchers thought the Y chromosome was what defined maleness: It contains genes that are responsible for sex determination, male development, and male fertility.

But now a team has discovered that X—the “female” chromosome—could also play a significant role in maleness. It contains scores of genes that are active only in tissue destined to become sperm. The finding shakes up our ideas about how sex chromosomes influence gender and also suggests that at least some parts of the X chromosome are playing an unexpectedly dynamic role in evolution.

“X Marks the Spot for Sperm Production,” ScientistIn addition to the headline-grabbing sex-linked angle, this study also revealed the surprisingly rapid evolution of genes in some regions of the X chromosome.

“Y chromosome sequence completed,” NatureIn 2003, some of the researchers who worked on this X chromosome study published work that similarly described the Y chromosome.

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